The present invention relates to a three-pole contact block, in particular with sudden disconnection and positive opening, utilisable in a switch sensitive to a pushing movement, in particular a position switch, a push button or analogous element.
Generally, such blocks comprise a casing for housing fixed contact parts terminated at one end by connection lands and carrying at another end a fixed contact together with a movable element provided with several contact bridges in such a way as to have at least one opening pole and one closure pole with the fixed contacts. The movable element is subjected to a push-button on the one hand and a spring system on the other, the whole being fitted to produce a positive opening and sudden opening and closure.
It is known from prior art how to implement a contact block in a multipole switch with a push button which acts upon a contact carrier with several superposed bridges, the bridges being mounted in a reversible way in order to ensure a xe2x80x9cnormally openxe2x80x9d (NO) or xe2x80x9cnormally closedxe2x80x9d (NC) function with the corresponding pole.
In certain cases it is preferable to confer to one of the poles of a three-pole switch an NO or NC function without having to modify the contact carrier.
The aim of the invention is to enable a multipole contact block to operate with at least one pole switchable from normally open state to normally closed state or the reverse, without modification of the layout of the contact carrier.
According to the invention, the connection lands are laid out according to at least three distinct connection planes, and the movable element has at least three contact bridges separated in such a way as to cooperate with fixed contacts located in two transversal contact planes and to move in two frontal planes; two contact bridges which are situated in the first frontal plane co-operating with fixed contact parts protruding on two connection planes, and the third contact bridge which is situated in the second frontal plane cooperating with the fixed contact parts protruding on the third connection plane. The third connection plane is in particular located in a median position between the two first connection planes.
Preferably the contact block is three-pole and the movable element that has four contact bridges with a balanced symmetrical arrangement, the fourth contact bridge being located in the second frontal plane and not co-operating with the fixed contact parts.
The movable element can be substituted at the fourth contact bridge by an elastic or mobile support part located in the second frontal plane relative to the third contact bridge located in this plane, so as to be displaced at the same time as the contact bridge located in the same transversal plane.
Advantageously the contact bridges located at different levels in a same frontal plane are acted upon by a single compression spring tending to separate them from each other.
In a simplified assembly embodiment, the movable element is mounted in the casing by introduction via an open rear face of the casing and a base is assembled, preferably clipped together with the casing to cover the rear face. The base can then have lugs or analogous maintenance elements which bear against the fixed contact parts ending at the rear plane to help to maintain them in a very simple way. A cover for insulating the terminals can be set, in particular clipped, on the front face of the casing.